Changes in surface levels of mercury, silver, tin, and copper of dental amalgam treated with carbamide peroxide and hydrogen peroxide in vitro

Abstract

Objectives. The effect of 10% carbamide peroxide or 10% hydrogen peroxide on the surface levels of mercury, silver, tin, and copper of amalgam fillings was tested in vitro with scanning electron microscopy and energy dispersive spectrometric microanalysis. Study design. Samples of amalgam were treated for 14 and 28 days with either 10% carbamide peroxide or 10% hydrogen peroxide solutions and compared with phosphate buffer controls. Results. A significant increase in mercury levels occurred after treatment with carbamide peroxide for 14 days ( p < 0.01) and 28 days ( p < 0.001) and after treatment with hydrogen peroxide for 28 days ( p < 0.001). A significant increase in silver levels occurred after treatment with carbamide peroxide for 14 days ( p < 0.05) and 28 days ( p < 0.01) and subsequent to treatment with hydrogen peroxide for 14 days ( p < 0.05) and 28 days ( p < 0.001). A significant reduction in tin levels occurred after treatment with hydrogen peroxide for 14 days ( p < 0.01) and 28 days ( p < 0.001), and after treatment with carbamide peroxide for 28 days ( p < 0.01). A significant reduction in copper levels was found after treatment with carbamide peroxide for 14 days ( p < 0.05). Conclusions. It appears that prolonged treatment with bleaching agents may cause microstructural changes in amalgam surfaces, possibly increasing exposure of patients to toxic byproducts.